一个嵌入式实时Java OS的设计及实现

针对嵌入式Inernet环境的特定要求，提出了一个嵌入式的实时Java OS—WebitJOS。WebitJOS在资源受限的嵌入式Internet环境下自身提供了对实时线程的调度、同步和异步处理的内部实现，消除了Garbage collection内存管理不确定性所产生的实时程序设计的障碍，并且提供了，从Java代码直接访问物理内存、寄存器及内存映射I／O的能力。根据嵌入式Internet系统对实时性、确定性的要求，用形式化语言描述了WebitJOS中实时线程及相关内存区的状态转换关系，并结合实例对WebitJOS相关的实时性能进行了测量和评价.

Design and implementation of an embedded real-time Java OS

In order to run Java code on the embedded Internet systems,Java runtimes must be integrated into these systems. In allusion to the special requirements of the embedded Internet environment,this paper presents an embedded real-time Java OS-WebiJOS. WebitJOS which runs on the resource-constrained embedded Internet system provides its own internal real-time thread implementation of the scheduling,synchronization,asynchronous processing,extends the memory management of the traditional Java virtual machine,eliminates an obstacle to real-time programming which is due to the unpredictable latencies introduced by the garbage collector,and allows real-time developers to directly accesses physical memory,registers,memory regions that have particular important characteristics,and memory-mapped I/O from Java code. According to requirements of the real-time and determinism which are necessary in the embedded Internet systems,state transitions of real-time threads and memory regions in WebitJOS are described in formal language,and measuring and evaluating the real-time performance of WebitJOS and one of its applications are made.